3 replies to this topic

[jprocess]

Dear All,
What does "High Pressure Recovery Control Valve" term refer to?
Why we shouldn't consider them in design for cases that there is the possibility of flashing and cavitation?
Cheers.

[jprocess]

Dear Sir,
I found this term in book:"Applied Instrumentation",chapter:control valve sizing.
Cheers.

[pasquale]

Dear all;

When a fluid passes through a control valve its velocity (therefore its pressure) changes.

In fact when the fluid passes through the valve seat the fluid's velocity increases because the area for the flow decreases (in stationary conditions the mass flowrate is constant) therefore the pressure decreases at its minimum value in the valve.

When the fluid is downstream the seat the area for the flow is bigger so the velocity decreases and the pressure increases. (obviously the pressure is lower than the valve inlet pressure).

The term high pressure recovery valve means that the fluid downstream the valve seat recovers a lot of pressure.

You can refer to Perry Chemical engineers handbook (instrumentation chapter) for more detail

Warm regard
Pasquale

[palusa]

HIgh pressure-recovery valves are kind of ctrl valves designed to mitigate/prevent cavitation effects: they are designed to minimize pressure loss by streamlining the flow passage.
This allows the valve to operate somewhat like a venturi where most of the energy contained in the high velocity at the throat is converted back into pressure energy in the diverging section of the valve.
Furthermore, cavitation in the venturi's throat begins when the average pressure is much closer to the liquid vapor pressure with respect to valves where cavitation can occur when the average pressure is significantly above the liquid vapor pressure.

_Lf_